The conventional subway line design method cannot address the issues of a large amount of demolition, complex construction, high risk, and high cost in the densely built areas under construction. This article innovates a line design method that combines a special scissors crossover with a curved islandtype misaligned platform, which not only meets the design needs of related disciplines such as architecture, structure, signal, track, train operation, and line but also allows subway lines to avoid dense buildings around the station flexibly. The results indicate that this innovative route design method can reduce demolition, increase construction clearance, reduce open excavation scale, reduce construction difficulty and risk, and reduce engineering investments. It provides technical guidance for areas with dense buildings, as well as demolition and construction difficulties around subway stations. The application to practical engineering cases demonstrates that this innovative line design method can yield economic, technical, and social benefits.

As property development above vehicle depots becomes increasingly common, it's crucial to address the construction and operational challenges this poses to the underlying facilities. This necessitates adaptive adjustments and optimizations in various aspects of depot design, including overall layout, fire safety, traffic management, utility systems, and vibration and noise mitigation. By comparing developed and undeveloped vehicle depots, this study proposes an optimization strategy centered on "one core concept and two principles." This approach aims to create favorable conditions for aboveground development while safeguarding the underground facilities' safety and environment, without compromising the depot's scale and functionality. The study outlines optimization strategies across multiple areas, including site selection, layout planning, maintenance procedures, emergency evacuation, ventilation and smoke control, and traffic flow. Specific recommendations include improving stationsection relationships, maximizing land use efficiency, implementing advanced maintenance equipment, and enhancing evacuation and smoke management systems. The ultimate goal is to minimize the negative impacts of aboveground development, fostering a harmonious relationship between the aboveground and underground facilities for mutual benefit.

The design standards for the roadbed structure of the metro depot have not been clearly defined in the Metro design specification (2013)," and the current practice of using the main line standard results in high and unreasonable costs. This study relies on the Zhengzhou Metro Tieluxi Depot project to conduct a numerical simulation analysis of dynamic loads under different subgrade structures and to study the variation law of the dynamic load distribution. The dynamic load generated by the ballastless track at the same train speed was smaller than that generated by the ballasted track. An increase in the thickness of the subgrade surface layer has a more substantial impact on reducing the dynamic load generated by the train operation. However, an excessively thick foundation increases roadbed stiffness, which is not conducive to stress dissipation. Hence, when the foundation thickness increases to a certain extent, the effect of reducing the dynamic loads gradually becomes less significant. The numerical simulation results show that the design scheme of the metro depot subgrade can appropriately adjust the parameters on the basis of "0.3 m+0.9 m" and "0.4 m+0.7 m", ensuring that the dynamic and static stress ratio of the subgrade is strictly less than 0.2, attaining the best level of safety and economy.

Concerning the noise pollution caused by the operation of the ground line of urban rail transit, the access line of the Zhongzhou Avenue depot in Zhengzhou Metro Line 5 is taken as an engineering example. The noise is tested in situ before and after the installation of sound barriers, and the noise reduction process is simulated with Virtual Lab software. The simulation results are in good agreement with the tested sound pressure level changing with the sound source frequency, and the accuracy of the acoustic simulation model and calculation method is verified. The insertion loss of sound pressure level is adopted to characterize the noise reduction effectiveness of the sound barrier, and further research are conducted on the noise reduction effectiveness of triangular wedge, QRD (Quadratic Residue Diffuser) sequence, PRD (Prime Root Diffuser) sequence and micro perforated panel PRD I composite sound barrier, and the results reveal that the wedge angle significantly impacts the noise reduction effectiveness of the triangular wedge sound barrier; greater irregularity enhances the diffusion effect for diffracted sound in PRD sound barriers, and PRD sound barriers exhibit better noise reduction effectiveness than QRD sound barriers; the overall noise reduction effectiveness of PRD type I sound barrier is slightly higher than that of PRD type II sound barrier, to reduce appropriately the design frequency of the diffusion body, increase the order, and expand the slot width can advance the noise reduction performance of the PRD type I sound barrier; to add micro perforated plate resonance sound absorption structure in the diffuser end groove of micro perforated panel PRD I composite can further improve the noise reduction of the end structure of diffuser, which would have an ideal application prospect for improving the noise environment of metro access lines.

Surface defect detection technology plays an essential role in railway inspections by effectively preventing railway accidents and ensuring operational safety. This study addresses the issues of poor detection accuracy and low sensitivity to small targets in existing railway defect detection technologies. For the mask regionbased convolutional neural network (Mask RCNN) algorithm model, a model improvement scheme was proposed by incorporating an attention mechanism. This scheme introduces a Channelwise Spatial Module (CSM) into the feature extraction network for segmentation defect detection, effectively eliminating interference, obtaining multiscale feature representations, and acquiring more spatial and shallow information, thereby enhancing the edge detection capability for surface defects on railway tracks. In the same experimental environment, compared with the Mask RCNN algorithm, after adding the CSM, the mAP value of the Mask RCNN model increased by 6.5%. Among them, the AP values for the recognition of "depression,” “crack,” and “fatigue wear" defects on railway tracks increased by 6.3%, 6.9%, and 6.1%, respectively. The horizontal segmentation effects of the three defects improved by 11.6%, 12.5%, and 12.9%, respectively, compared with the Faster RCNN model, and the segmentation effects of the three defects enhanced by 8.8%, 10.0%, and 10.3%, respectively. This study demonstrates that the Mask RCNN model with CSM can better recognize three types of defects, enhance the detection accuracy and sensitivity to small targets, provide more secure and robust technical support, and guarantee intelligent track inspection.

This study focuses on a rectangular prefabricated station structure scheme developed and applied for the first time to the Shenzhen Phase V Project. Combined with the evolution process of the prefabricated structure scheme with dry connections, this paper introduces in detail the section design scheme of the rectangular structure scheme, structural partitioning and joint, bracing system of the beamcolumn, and static and dynamic performances. The rectangular prefabricated station structure scheme can be applied to different station width requirements, and an adjustable template is used to effectively improve the universality of the rectangularstructure components. Simultaneously, the rectangular structure can be expanded to accommodate different types of stations, such as threelayer twospan or twolayer threespan. Additionally, the bending bearing capacity of a rectangular assembled station joint was verified by a fullscale joint test, and the adaptability of the theoretical calculation method of the existing joint research to structural size changes was verified. The results of this study are intended to provide a reference and experience for subsequent prefabricated structure designs and engineering applications.

The mechanism of the geological deformation caused by shield tunneling construction was combined with a threedimensional numerical simulation method to simulate the displacement of bridge piles during the smallangle side crossing of highspeed railway bridge group piles in subway shield tunnels constructed in sandy areas. Analyses were conducted on the mechanism of the impact of metro shield tunnels on highspeed railway bridges when the shield reaches the front of the piles, reaches the piles, and moves past the piles, as well as when the shield tail is detached and after the shield passes the piles. Three protection plans were then proposed for highspeed railway bridges, which included isolation pile measures, geological reinforcement measures, and isolation piles + geological reinforcement. Threedimensional numerical simulations were used to analyze the entire process of shield tunnel boring through the pile groups of highspeed railway bridges under the conditions of no protection scheme and when adopting the above three protection schemes. The findings revealed that without protective measures or with the sole use of ground reinforcement or isolation piles, the deformation of a highspeed railway bridge exceeds the allowable standards during the lateral passage of a shield tunnel. However, with the implementation of both isolation piles and ground reinforcement, the deformation remains within the prescribed limits. After the scheme comparison, the design scheme of isolation piles and ground reinforcement were ultimately adopted for implementation. During the onsite implementation, the entire process was monitored, and the monitoring results were consistent with the numerical calculations, verifying the rationality of the highspeed railway bridge protection plan.

To provide a theoretical basis and reference for crack control during construction, this study first monitored the construction of side walls by embedding temperature and stress sensors. The measured data were then compared with the Midas civil finite element model, the law for a temperature field, and the stress field during the construction of the side walls. The field monitoring and numerical analysis showed that the hydration heat reaction of the concrete in the early stage was relatively fast, reaching its maximum value only 20 h after pouring. The temperature was high in summer, and the cooling rate was relatively slow at approximately 0.40 °C/h. However, the cooling rate of the middle layer was relatively fast. The time at which the compressive stress reached its maximum value was close to that at which the temperature reached its maximum value. Subsequently, it entered the shrinkage deformation stage. After the critical condition of zero stress occurred, the tensile stress gradually increased with a continuous decrease in temperature, and the tensile stress at each measuring point tended to be stable 50 h after pouring. The finite element model results were close to the field monitoring data. Thus, it could play a role in the prediction of and theoretical basis for fractures. It could also be used as a reference for actual fracture control in engineering.

In the overall structure of a shield tunnel, the joint of the pipe segments is the weakest part of the waterproofing system, and its waterproofing performance directly influences the stability and service life of the entire tunnel. With continuous innovation and changes in structural design and construction methods, the occurrence of water leakage or sealing gasket damage at the joints of pipe segments has become increasingly severe. Therefore, research and optimization of waterproofing performance are crucial. This study begins with the waterproof principle of elastic sealing gaskets and deeply analyzes the factors that affect joint leakage, based on which specific optimization measures were proposed for the waterproof performance of pipe joints. Finally, to verify the actual effectiveness of these optimization measures, empirical research was conducted on a new type of shield tunnel project in Jiangxinzhou, Nanjing. The main conclusions of the study are as follows: the physical properties and durability of EPDM gaskets must strictly comply with regulatory requirements; The adhesive work of the onsite sealing gasket and the tensile deformation of the onsite pipe segment assembly on the sealing gasket is essential factors impacting the leakage of water at the joint; The solid section structure at the corner of a largediameter high water pressure shield tunnel requires to be optimized to avoid issues such as corner accumulation and stress concentration caused by the crosssectional size of the sealing gasket; The monitoring results after the tunnel is completed indicate that the optimized shield tunnel not only has good forming quality but also has a much better waterproof effect than traditional shield tunnels. This study not only provides a theoretical basis and practical guidance for the waterproof design of shield tunnel segment joints but also provides a valuable reference and inspiration for similar projects.

Subway carriages are ventilated from the outside world through fans, which regulate the temperature, humidity, and wind speed of the internal environment of the carriages, improve air quality, and enhance the thermal comfort of passengers. Due to the limited number of applicable thermal comfort evaluation indices, accurately determining the thermal comfort of subway car occupants in transient environments is challenging. This paper first focuses on occupants of a Btype subway compartment as the research subject and proposes the joint application of DRBerkeley thermal comfort evaluation indexes by considering both airflow comfort and heat sensation. The study then employs the Stolwijk physiological model of human thermal regulation to construct a threedimensional model of the amplitudeflow fan and an overall simulation model of the subway compartment. Finally, using CFD software, STARCCM+, the study analyzes the effects of different fan speeds, fan hood disturbance speeds, and fan air supply temperatures on the microenvironment and thermal comfort of the occupants under seven different conditions during the summer. The results show that the DRBerkeley thermal comfort evaluation indexes can reasonably evaluate the thermal comfort of subway compartments under the premise of meeting the airflow comfort in summer; increasing the fan speed, reducing the hood disturbance speed, and reducing the fan air supply temperature can improve the thermal comfort of the occupants; in the seven working conditions, the fan speed of 1,400 rpm, the hood disturbance speed of 3.25 rpm, and the air supply temperature of 20°C have a uniform temperature and speed distribution in the compartments. The temperature and velocity distributions in the cabin were uniform, the occupant microenvironmental heat flow field was optimal, and thermal comfort was 0.766. This method can solve the occupant thermal comfort problem more comprehensively, which is of some reference significance for optimizing the thermal flow field environment in subway compartments and upgrading occupant thermal comfort.